Dart pub

fluttie 0.1.2

fluttie: Lottie for flutter

Fluttie (github, pub)
is a flutter plugin for displaying animations
created in Lottie. Even complex animations can
be displayed without having to write long custom rendering code.
The library can render the animations by piping the output from the Lottie
Android library into a Flutter texture.

You can download
a small Flutter app for Android showing what Fluttie looks like in action. This
app can also be used to easily preview animations from lottiefiles.com,
which might be handy when deciding what animations to use.

Please note: At the moment, this plugin does not support iOS devices.

Things to keep in mind when using this:

The plugin is in an early state and there will be breaking API changes

No iOS support yet

Loading animations from files is taking quite some time at the moment as the dart
code needs to send the full animation declaration to the plugin. When
this issue gets fixed, it might be faster.
The time required also seems to be a lot shorter in non-debug builds.

Due to a delay between the dart code and the native backend, controlling
multiple animations can be a bit laggy. Rendering multiple animations will
also heavily reduce your apps framerate (Using multiple threads to circumvent this has already been implemented, but crashes Flutter).

Animation widgets need a fixed size for now

Do not re-use animations, as this can crash your app. Instead, save the output
of loadAnimationFromResource() and construct a new animation whenever you need
to.

Getting Started

The example included
contains a basic, but throughoutly commented, app illustrating how to include,
load and show animations in Fluttie.

In order to use animations with fluttie, you will need a json file
containing the composition for your animation. You can either export it using
an AfterEffects plugin (see instructions)
or grab some at lottiefiles.com.
Place the file in an folder inside your project and add it in the assets part of your pubspec.yaml.
If you haven't already done so, add Fluttie to your projects dependencies:

dependencies:
fluttie: ^0.1.2

In order to display animations in Flutter, you will have the plugin to load
a composition first:

You can then use that composition to create a new AnimationController,
like this:

emojiAnimation = await instance.prepareAnimation(emojiComposition)

You can also set the duration of your animation and configure looping while
preparing the animation by using the optional parameters of prepareAnimation.
After having your animation controller ready, you can include it as a widget:

Questions and bugs

As the library is in an early version, there will be things not working like
they should. If you encounter a bug, have a question or want some features implemented,
please don't hesitate to create an issue.
Of course, would absolutely appreciate any contributions as pull requests.

0.1.2

Make the plugin only react to activity lifecircle changes that involve the
main flutter activity.

0.1.1

Fix crashes occuring when disposing animations

Ability to unpause animations without having to restart them

0.1.0

Render small animations in high quality by using the preferredSize
parameter of Fluttie.prepareAnimation.

Reduce resource usage by pausing aimations while the app is in background

Implement multithreaded rendering, not yet enabled because of an issue in the
Flutter framework.

0.0.1

First release with basic functionality

example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:fluttie/fluttie.dart';
void main() => runApp(new MyApp());
/// An example app showcasing the features of fluttie animations. It should
/// show a emoji animation at the top and a bar of stars below it. When tapping
/// on a star, all the stars to the left should be filled in a beautiful animation.
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> {
/// Animation to display a shocked emoji taken from lottiefiles.com
FluttieAnimationController shockedEmoji;
/// A list of animations representing the stars shown in a horizontal line.
/// They will be started when the user tabs on one of them.
List<FluttieAnimationController> starAnimations = [];
/// The amount of stars currently selected in the line. Used to compute the
/// difference on a tap.
int currentlySelectedStars = 0;
/// If we're ready to show the animations. Set to true after they have been
/// loaded by the plugin.
bool ready = false;
/// The performance overlay can be triggered by tapping on the icon on the
/// right-hand side of the toolbar. It can be used to invastigate the
/// performance impact of running different animations.
bool showPerformanceOverlay = false;
@override
initState() {
super.initState();
/// Load and prepare our animations after this widget has been added
prepareAnimation();
}
@override
dispose() {
super.dispose();
/// When this widget gets removed (in this app, that won't happen, but it
/// can happen for widgets using animations in other situations), we should
/// free the resources used by our animations.
shockedEmoji?.dispose();
starAnimations.forEach((anim) => anim.dispose());
}
// async because the plugin will have to do some background-work
prepareAnimation() async {
// Checks if the platform we're running on is supported by the animation plugin
bool canBeUsed = await Fluttie.isAvailable();
if (!canBeUsed) {
print("Animations are not supported on this platform");
return;
}
var instance = new Fluttie();
// Load our first composition for the emoji animation
var emojiComposition = await instance.loadAnimationFromResource(
"resources/animations/emoji_shock.json",
bundle: DefaultAssetBundle.of(context)
);
// And prepare its animation, which should loop infinitely and take 2s per
// iteration. Instead of RepeatMode.START_OVER, we could have choosen
// REVERSE, which would play the animation in reverse on every second iteration.
shockedEmoji = await instance.prepareAnimation(emojiComposition,
duration: const Duration(seconds: 2),
repeatCount: const RepeatCount.infinite(), repeatMode: RepeatMode.START_OVER);
// Load the composition for our star animation. Notice how we only have to
// load the composition once, even though we're using it for 5 animations!
var composition = await instance.loadAnimationFromResource(
"resources/animations/star.json",
bundle: DefaultAssetBundle.of(context)
);
// Create the star animation with the default setting. 5 times. The
// preferredSize needs to be set because the original star animation is quite
// small. See the documentation for the method prepareAnimation for details.
for (int i = 0; i < 5; i++) {
starAnimations.add(
await instance.prepareAnimation(
composition,
preferredSize: Fluttie.kDefaultSize
)
);
}
// Loading animations may take quite some time. We should check that the
// widget is still used before updating it, it might have been removed while
// we were loading our animations!
if (mounted) {
setState(() {
ready = true; // The animations have been loaded, we're ready
shockedEmoji.start(); //start our looped emoji animation
});
}
}
void animateStarChange(int updated) {
/* When the amount of stars that are selected changes, we will have to
play or stop animations in order to reflect that in the UI. For that, we
start the animation for each star that was not previously selected but
should be selected now (i >= old) and (i < currentlySelectedStars).
If the amount to show has been reduced, we can simply rewind the animation
to the beginning, as that will show a hollow star not selected.
Notice how i refers to the index starting at 0, while the amount should
start at 1.
*/
setState(() {
int old = this.currentlySelectedStars;
currentlySelectedStars = updated;
for (int i = 0; i < 5; i++) {
if (i < currentlySelectedStars) { //Star needs to be shown
if (i >= old) //Star would otherwise already be shown
starAnimations[i].start();
} else { //Remove star, reset to beginning
starAnimations[i].stopAndReset(rewind: true);
}
}
});
}
/// Builds a widget animating the star at the specified index.
Widget buildStar(int i) {
return new Flexible(
child: new GestureDetector(
onTap: () {
// Update the amount of stars that have been selected when this star
// is tapped.
int amountOfStars = i + 1;
animateStarChange(amountOfStars);
},
child: new FluttieAnimation(starAnimations[i])
)
);
}
/// When we're ready to show the animations, this method will create the main
/// content showcasing them.
Widget buildStarContent(BuildContext context) {
return new Column(
children: [
//Display the emoji animations at the top
new FluttieAnimation(shockedEmoji),
//followed by a row of 5 stars that can be tapped
new Row(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
buildStar(0), buildStar(1), buildStar(2), buildStar(3), buildStar(4)
],
),
// Use a Flexible widget so that the rest will be on the bottom
new Flexible(child: new Container()),
// And display some credits showing where the animations are taken from
new RichText(
text: new TextSpan(
children: [
new TextSpan(
text: "Animations taken from ",
style: Theme.of(context).textTheme.body1.copyWith(color: Colors.grey)
),
new TextSpan(
text: "lottiefiles.com",
style: Theme.of(context).textTheme.body2
)
]
),
),
new Padding(padding: const EdgeInsets.only(bottom: 10.0)),
],
);
}
@override
Widget build(BuildContext context) {
// Display the main content, or - when we're not ready for that yet - a text
// informing the user that the animations are being prepared.
Widget content = ready ? buildStarContent(context) : new Text("Loading animations");
return new MaterialApp(
showPerformanceOverlay: this.showPerformanceOverlay,
home: new Scaffold(
appBar: new AppBar(
title: new Text('Fluttie example'),
actions: [
// Button to toggle the performance overlay
new IconButton(
icon: const Icon(Icons.build),
onPressed: () {
setState(() {
showPerformanceOverlay = !showPerformanceOverlay;
});
},
)
],
),
body: new Center(child: content)
),
);
}
}